METHOD FOR PURIFYING FERRIC CHLORIDE

Abstract

A method for purifying ferric chloride, the method including: 1) adding an oxidant to an aqueous solution of an iron-containing chloride for oxidation of Fe.sup.2+, to yield a ferric chloride solution; 2) adding industrial hydrochloric acid and butyl acetate to the ferric chloride solution, shaking and resting a mixture of the ferric chloride solution, the industrial hydrochloric acid, and butyl acetate for phase separation, to yield an organic phase and an aqueous phase; 3) adding a stripping agent to the organic phase, shaking, and resting a mixture of the stripping agent and the organic phase; and collecting an aqueous phase including ferric chloride; and 4) evaporating and concentrating the aqueous phase including ferric chloride, removing butyl acetate, to yield purified ferric chloride.

Claims

1. A method, comprising: 1) adding an oxidant to an aqueous solution of an iron-containing chloride for oxidation of Fe.sup.2+, to yield a ferric chloride solution; 2) adding industrial hydrochloric acid and butyl acetate to the ferric chloride solution, shaking and resting a mixture of the ferric chloride solution, the industrial hydrochloric acid, and butyl acetate for phase separation, to yield an organic phase and an aqueous phase; 3) adding a stripping agent to the organic phase, shaking, and resting a mixture of the stripping agent and the organic phase; and collecting an aqueous phase comprising ferric chloride; and 4) evaporating and concentrating the aqueous phase comprising ferric chloride, removing butyl acetate, to yield purified ferric chloride.

2. The method of claim 1, wherein in 1), the iron-containing chloride is ferrous chloride, ferric chloride, or a mixture thereof.

3. The method of claim 1, wherein in 1), the oxidant is oxygen, air, ozone, sodium chlorate, hydrogen peroxide, chlorine, or a mixture thereof.

4. The method of claim 1, wherein in 2), a volume ratio of the ferric chloride solution to the industrial hydrochloric acid to butyl acetate is 1: 2-6:1-4.

5. The method of claim 4, wherein in 2), a hydrochloric acid concentration of the mixture of the ferric chloride solution, the industrial hydrochloric acid, and butyl acetate is not less than 6 mol/L.

6. The method of claim 1, wherein in 2), the organic phase is extracted repeatedly to improve iron concentration therein.

7. The method of claim 1, wherein in 2), the aqueous phase is extracted for 3-5 stages to allow iron in the aqueous phase to enter the organic phase.

8. The method of claim 1, wherein in 3), the stripping agent is pure water or a 0.5-1 wt. % hydrochloric acid aqueous solution.

9. The method of claim 1, wherein in 4), the aqueous phase comprising ferric chloride is evaporated and concentrated at a temperature no less than 80° C. for at least 10 min.

Description

DETAILED DESCRIPTION

[0025] To further illustrate, embodiments detailing a method for purifying ferric chloride (iron(III) chloride) are described below. It should be noted that the following embodiments are intended to describe and not to limit the disclosure.

Example 1

[0026] The disclosure provides a method for purifying ferric chloride (iron(III) chloride), which is carried out as follows:

[0027] 1) 1 kg of ferrous chloride solution A.sub.0 was chlorinated with chlorine until Fe.sup.2+ was completely oxidized, to yield a ferric chloride solution;

[0028] 2) 3 kg of industrial hydrochloric acid and 2 kg of butyl acetate were added to the ferric chloride solution; the resulting mixture was shaken and rested for phase separation, and an organic phase was obtained;

[0029] 3) 1 kg of pure water was added to the organic phase for stripping; the resulting solution was rested for phase separation; an aqueous phase comprising ferric chloride and small impurities was obtained, and the organic phase was returned to the extraction equipment for recycling; and

[0030] 4) the aqueous phase comprising ferric chloride and small impurities was boiled and evaporated for 10 min, to yield high-purity ferric chloride A.

[0031] The experimental data is shown in Table 1, in which the detection limit of total organic carbon (TOC) detector is 3 mg/L:

TABLE-US-00001 TABLE 1 High-purity Ferrous chloride ferric Product index solution A.sub.0 chloride A Fe, % 14.2 9.26 HCl, % 2.21 0.31 Cu, ppm 3689 1.18 Ni, ppm 2217 Not detected (<0.1) Zn, ppm 4324 2.86 Cr, ppm 5658 1.66 Mn, ppm 7869 0.82 TOC, mg/L Not detected (<3 mg/L) Not detected (<3 mg/L)

Example 2

[0032] The disclosure provides a method for purifying ferric chloride (iron(III) chloride), which is carried out as follows:

[0033] 1) 2 kg of ferrous chloride solution A.sub.0 was chlorinated with chlorine until Fe.sup.2+ was completely oxidized, to yield a ferric chloride solution;

[0034] 2) 3 kg of industrial hydrochloric acid and 2 kg of butyl acetate were added to 1 kg of the ferric chloride solution; the resulting mixture was shaken and rested for phase separation, and a first organic phase was obtained;

[0035] 3) 1 kg of the ferric chloride and 3 kg of industrial hydrochloric acid were added to the first organic phase, shaken, and rested for phase separation, and a second organic phase was obtained;

[0036] 4) 1 kg of pure water was added to the second organic phase for stripping; the resulting solution was rested for phase separation, yielding a first aqueous phase B.sub.1 comprising ferric chloride and small impurities, and a third organic phase; 1 kg of pure water was added to the third organic phase for stripping; the resulting mixture was rested for phase separation, yielding a second aqueous phase C.sub.1 comprising ferric chloride and ultralow impurities, and a fourth organic phase; the fourth organic phase was returned to the extraction equipment for recycling; and

[0037] 5) the first aqueous phase B.sub.1 comprising ferric chloride and small impurities and the second aqueous phase C.sub.1 comprising ferric chloride and ultralow impurities were boiled and evaporated for 15 min, to yield high-purity ferric chloride B, high-purity ferric chloride C, respectively.

[0038] The experimental data is shown in Table 2:

TABLE-US-00002 TABLE 2 High-purity High-purity Ferrous chloride ferric ferric Product index solution A.sub.0 chloride B chloride C Fe, % 14.2 11.18 7.27 HCl, % 2.21 0.32 0.20 Cu, ppm 3689 1.25 Not detected (<0.1) Ni, ppm 2217 Not detected Not detected (<0.1) (<0.1) Zn, ppm 4324 2.65 0.24 Cr, ppm 5658 1.54 Not detected (<0.1) Mn, ppm 7869 0.97 0.13 TOC, mg/L Not detected Not detected Not detected (<3 mg/L) (<3 mg/L) (<3 mg/L)

Example 3

[0039] The disclosure provides a method for purifying ferric chloride (iron(III) chloride), which is carried out as follows:

[0040] 1) 1 kg of ferrous chloride solution A.sub.0 was mixed with appropriate sodium chlorate and hydrochloric acid until Fe.sup.2+ was completely oxidized, to yield a ferric chloride solution;

[0041] 2) 2 kg of industrial hydrochloric acid and 1 kg of butyl acetate were added to the ferric chloride solution; the resulting mixture was shaken and rested for phase separation, and an organic phase was obtained;

[0042] 3) 1 kg of pure water was added to the organic phase for stripping; the resulting solution was rested for phase separation; an aqueous phase Di comprising ferric chloride and small impurities was obtained, and the organic phase was returned to the extraction equipment for recycling; and

[0043] 4) the aqueous phase Di comprising ferric chloride and small impurities was boiled and evaporated for 15 min, to yield high-purity ferric chloride D.

[0044] The experimental data is shown in Table 3:

TABLE-US-00003 TABLE 3 High-purity Ferrous chloride ferric Product index solution A.sub.0 chloride A Fe, % 14.2 9.17 HCl, % 2.21 0.24 Cu, ppm 3689 1.12 Ni, ppm 2217 Not detected (<0.1) Zn, ppm 4324 2.65 Cr, ppm 5658 1.72 Mn, ppm 7869 0.86 TOC, mg/L Not detected (<3 mg/L) Not detected (<3 mg/L)

Example 4

[0045] The disclosure provides a method for purifying ferric chloride (iron(III) chloride), which is carried out as follows:

[0046] 1) 1 kg of a mixed solution Ai comprising ferrous chloride and ferric chloride was mixed with appropriate sodium chlorate and hydrochloric acid until Fe.sup.2+ was completely oxidized, to yield a ferric chloride solution;

[0047] 2) 4 kg of industrial hydrochloric acid and 3 kg of butyl acetate were added to the ferric chloride solution; the resulting mixture was shaken and rested for phase separation, and an organic phase was obtained;

[0048] 3) 1 kg of 0.5% dilute acid water was added to the organic phase for stripping; the resulting solution was rested for phase separation; an aqueous phase E comprising ferric chloride and small impurities, and the organic phase was returned to the extraction equipment for recycling; and

[0049] 4) the aqueous phase E comprising ferric chloride and small impurities was boiled and evaporated for 30 min, to yield high-purity ferric chloride F.

[0050] The experimental data is shown in Table 4:

TABLE-US-00004 TABLE 4 Mixed solution A.sub.1 Aqueous phase E comprising ferrous comprising ferric High-purity chloride and ferric chloride and small ferric Product index chloride impurities chloride F Fe, % 15.34 11.26 14.82 HCl, % 1.28 0.58 Cu, ppm 5879 0.63 Ni, ppm 4346 Not detected (<0.1) Zn, ppm 6362 1.21 Cr, ppm 8394 Not detected (<0.1) Cd, ppm 1.82 0.02 As, ppm 3.2 0.011 Pb, ppm 3.68 0.06 Hg, ppm 0.63 0.002 Co, ppm 3.66 0.09 V, ppm 1.38 0.06 Sn, ppm 1.96 0.10 Na, ppm 14.3 4.82 5.8 Mg, ppm 26.7 1.2 K, ppm 32.8 2.3 Ca, ppm 53.9 2.6 Mn, ppm 8682 1.02 TOC, mg/L Not detected 486 Not detected Ferrous (Fe), % 6.21 <0.01 <0.01 Sulfate >0.1 — ≤0.01 (SO.sub.4), % Nitrate >0.1 — ≤0.01 (NO.sub.3), % Phosphate >0.1 — ≤0.01 (PO.sub.4), %

Example 5

[0051] The disclosure provides a method for purifying ferric chloride (iron(III) chloride), which is carried out as follows:

[0052] 1) 1 kg of a mixed solution Ai comprising ferrous chloride and ferric chloride was mixed with appropriate sodium chlorate and hydrochloric acid until Fe.sup.2+ was completely oxidized, to yield a ferric chloride solution;

[0053] 2) 6 kg of industrial hydrochloric acid and 4 kg of butyl acetate were added to the ferric chloride solution; the resulting mixture was shaken and rested for phase separation, and an organic phase was obtained;

[0054] 3) 1 kg of 0.5% dilute acid water was added to the organic phase for stripping; the resulting solution was rested for phase separation; an aqueous phase comprising ferric chloride and small impurities, and the organic phase was returned to the extraction equipment for recycling; and

[0055] 4) the aqueous phase comprising ferric chloride and small impurities was boiled and evaporated for 60 min, to yield high-purity ferric chloride G.

[0056] The experimental data is shown in Table 5:

TABLE-US-00005 TABLE 5 Mixed solution A.sub.1 comprising High-purity ferrous chloride ferric Product index and ferric chloride chloride G Fe, % 15.34 14.82 HCl, % 1.28 0.58 Cu, ppm 5879 0.63 Ni, ppm 4346 Not detected (<0.1) Zn, ppm 6362 1.21 Cr, ppm 8394 Not detected (<0.1) Cd, ppm 1.82 0.02 As, ppm 3.2 0.011 Pb, ppm 3.68 0.06 Hg, ppm 0.63 0.002 Co, ppm 3.66 0.09 V, ppm 1.38 0.06 Sn, ppm 1.96 0.10 Na, ppm 14.3 5.8 Mg, ppm 26.7 1.2 K, ppm 32.8 2.3 Ca, ppm 53.9 2.6 Mn, ppm 8682 1.02 TOC, mg/L Not detected Not detected Ferrous (Fe), % 6.21 <0.01 Sulfate (SO.sub.4), % >0.1 ≤0.01 Nitrate (NO.sub.3), % >0.1 ≤0.01 Phosphate (PO.sub.4), % >0.1 ≤0.01

[0057] As shown in the experimental data of Examples 1-5, when the raw materials contain much more heavy metal impurities, for example, Cu, Ni, Zn, Cr and Mn, through controlling the usage amount of hydrochloric acid and butyl acetate, the metal impurities can be completely separated from the solution by butyl acetate extraction, and the organic matter residual (that is, butyl acetate) in ferric chloride after stripping can be removed by evaporation. The purified and concentrated ferric chloride can meet the requirements of drinking water treatment, pharmaceutical intermediates, analytical testing and precision etching industry.

[0058] Effect of Solution Acidity on the Single Extraction of Iron with Butyl Acetate

[0059] Fe.sup.2+ can be completely complexed by 3.6 mol/L hydrochloric acid. Therefore, the test starts with 4 mol/L, and the industrial hydrochloric acid is generally 10-11 mol/L.

[0060] 10 mL of FeCl.sub.3 sample was mixed with hydrochloric acid and water to form 30 mL of FeCl.sub.3 solution with an acidity of 4, 5, 6, 7, 8, 9 mol/L, respectively, first extracted with 18 mL of butyl acetate and then stripped with 10 mL of water. Thereafter, the aqueous phase was measured, and the experimental data is shown in Table 6:

TABLE-US-00006 TABLE 6 Raw Product mate- Acidity, mol/L index rials 4 5 6 7 8 9 Cu, ppm 4698 83 22 1.3 1.6 1.5 1.00 Ni, ppm 5543 46 13 Not Not Not 0.13 detected detected detected Zn, ppm 8657 97 34 2.1 2.3 1.8 2.0 Cr, ppm 6692 65 18 Not Not 0.21 Not detected detected detected Mn, ppm 9264 78 21 0.95 0.86 0.77 1.23 Cd, ppm 2.64 0.22 0.09 0.02 0.01 0.02 0.03 As, ppm 3.39 0.34 0.07 0.03 0.03 0.04 0.02 Pb, ppm 4.26 0.54 0.11 0.02 0.03 0.02 0.01 Hg, ppm 0.89 0.12 0.02 0.01 0.005 0.003 0.006 Co, ppm 4.26 0.54 0.11 0.04 0.02 0.03 0.05 V, ppm 3.17 0.66 0.08 0.06 0.03 0.04 0.08 Sn, ppm 2.62 0.32 0.06 0.05 0.02 0.01 0.02 Na, ppm 4899 24 7.3 2.5 2.7 1.8 2.2 Mg, ppm 268 11 5.2 2.2 2.9 1.6 2.1 K, ppm 683 30 6.6 4.6 3.8 2.5 3.1 Ca, ppm 1597 12 8.2 5.1 4.6 6.1 4.3 Sulfate 1 0.08 0.05 <0.01 <0.01 <0.01 <0.01 (SO.sub.4), % Nitrate 1 0.05 0.03 <0.01 <0.01 <0.01 <0.01 (NO.sub.3), % Phosphate 1 0.05 0.03 <0.01 <0.01 <0.01 <0.01 (PO.sub.4), %

[0061] As shown in Table 6, when the acidity of the solution is low, butyl acetate can extract a small amount of metal impurities. When the acidity of the solution is more than 6 mol/L, ferric chloride can be purified better.

[0062] In the disclosure, hydrochloric acid is added to improve the acidity of the solution, thus improving the single extraction of (FeCl.sub.4).sup.− through butyl acetate. After detection, nearly 20 kinds of metal impurities are removed one time, and a variety of toxic and harmful impurity metals can be reduced to less than 1 ppm, which can meet the requirements of various high-purity ferric chloride, such as precision etching, drinking water treatment, pharmaceutical intermediates, and analysis and testing. The method involves simple equipment, is free from the purity of raw materials, the extractant can be reused, and the purification cost is relatively low.

[0063] It will be obvious to those skilled in the art that changes and modifications may be made, and therefore, the aim in the appended claims is to cover all such changes and modifications.